Effect of endogenous hormones, antisperm antibody and oxidative stress on semen quality of crossbred bulls.

The present study was designed to evaluate the effect of factors like hormones, antisperm antibody (ASA), and oxidative stress and its relation with semen quality in crossbred bulls. Ejaculates from two bulls were categorized into good (n = 12) and poor (n = 12) based on initial progressive motility, that is, ≥70% and ≤50%, respectively. The level of hormones like Testosterone (p < 0.05) and PGE2 (p < 0.01) was significantly higher in good-quality ejaculates compared to poor-quality ejaculates; however, estradiol (p < 0.05), progesterone, oxidative stress, and ASAs were significantly higher (p < 0.01) in poor-quality ejaculates compared to good-quality ejaculates. Therefore, it could be concluded that oxidative stress and hormonal imbalance might have resulted in high number of dead and defective spermatozoa which was ultimately responsible for poor quality semen ejaculates.

Incubation with Cholesterol-loaded Cyclodextrin and Subsequent Dilution in Partially Deoxygenated Extender Improves the Freezability of Cross-bred Bull Sperm.

BACKGROUND: The cryopreservation process induces osmotic stress, membrane changes and production of reactive oxygen species resulting in damage to the spermatozoa. Together, the presence of oxygen in the extender aggravates the oxidative stress that further reduces the cryosurvival rate of sperm cells. OBJECTIVE: To study the combined effect of cholesterol loaded cyclodextrin (CLC) and partial deoxygenation on post-thaw semen quality in crossbred bulls. MATERIALS AND METHODS: A total of 18 ejaculates from three crossbred bulls with >3+ mass motility and >70% individual progressive motility were utilized for the study. Each semen sample was divided into four groups: Group I (containing extender without partial deoxygenation or CLC addition); Group II (extender containing 3 mg CLC/120X106 spermatozoa); Group III (extender containing 3 mg CLC/120X106 spermatozoa and 4 ppm dissolved oxygen (DO) level); Group IV (extender containing 3 mg CLC/120X106 spermatozoa and 6 ppm DO level). The samples in each group were finally extended to have 80×106 progressive motile sperm/mL of extender, filled and sealed in French mini straws (0.25 mL) and frozen following equilibration. The effect of CLC addition and partial deoxygenation was assessed at fresh (post-dilution), pre-freeze and post-thaw stages by evaluating various variables [sperm motility, viability, hypo-osmotic swelling (HOS) response, acrosomal integrity, capacitation status and mitochondrial membrane potential (MMP)]. RESULTS: The sperm population was significantly more positive for motility, viability, HOS response, acrosome intactness, high MMP and had less capacitation-like changes in groups supplemented with CLC and partially deoxygenation. However, the positive effect was most pronounced in the group that had extender with CLC+4 ppm DO. CONCLUSION: Partial deoxygenation of extender, and CLC addition in combination, could be part of a rationale for improving post-thaw semen quality in cross-bred bulls.